Summary of model selection testing for interactions between multiple stressors on macroinvertebrate abundance and richness and the SPEAR and BMWP indices, based on the Akaike information criterion corrected for sample size (AICc).

Models are ordered from the best to the poorest fit according to Akaike weights (wi). K, number of estimated parameters for each model; Δi (delta AICc), difference in AICc value relative to the best model; wi, probability that a model is the best among the whole set of models. For each response variable, five models were constructed, which are ordered from the simplest model without interactions (model 1: null model, with no interactions) to the most complex one (model 5, containing the 3-way interaction). Models differ in the number of parameters according to the most parsimonious combination of structure and terms described in S9 Table. PT, pesticide toxicity (Tumax); SE, sedimentation index; NE, nutrient enrichment (SRP).